Retirement Plans - Assumptions Used to Determine the Net Periodic Benefit Cost and Benefit Obligations (Details) - Pension Plans, Defined Benefit [Member]	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Discount rate for net periodic pension cost	4.30%	3.90%	4.70%
Discount rate for benefit obligations	4.00%	4.30%	3.90%
Expected long-term return of plan assets	7.75%	7.50%	8.00%